through Houston, following a route from Katy through Memorial, Rice Military, Downtown, the East End, Denver Harbor, and Channelview before meeting the San Jacinto River at Galveston Bay. The broad eastern stretch of the river, known as the Houston Ship Channel, plays an essential role in the Port of Houston and is home to one of the largest petrochemical refining complexes in the United States. Buffalo Bayou's environs are also home to significant amounts of parkland, including linear parks such as Terry Hershey Park and Buffalo Bayou Park which serve as corridors for walking and bicycling. White Oak Bayou, a major tributary of the Buffalo, has its source in Jersey Village and travels southeast, through Inwood Forest, Oak Forest, and Houston Heights. Brays Bayou, another major tributary to the south, originates near Mission Bend and travels through Alief, Sharpstown, Meyerland, Braeswood Place, the Texas Medical Center, Riverside Terrace, and the East End before meeting Buffalo Bayou at Harrisburg. Two more significant tributaries of Buffalo Bayou flow through parts of Houston outside the Interstate 610 loop. Greens Bayou, which originates in far northwest Houston near Willowbrook, flows for through Greenspoint and undeveloped areas of northeastern Harris County. Sims Bayou, which has its source near Missouri City southwest of Houston, flows for past Almeda, Sunnyside, South Park, and Manchester. Houston's topography is further defined by a large number of creeks and ditches. Overall, this intricate system of waterways is essential to flood control; Houston is well known as one of the most flood-prone cities in the United States. Since the mid-20th century, the United States Army Corps of Engineers, in cooperation with the city and Harris County Flood Control District, has channelized, paved, widened, and deepened extensive sections of all of the five major bayous specified above, with the notable exception of some parts of the Buffalo near Memorial. The Buffalo Bayou watershed also features two flood control reservoirs, Addicks Reservoir and Barker Reservoir, which retain large amounts of water after extreme rainfall events. Cypress Creek drains a significant portion of northern Harris County. The river flows for through the suburban areas of Cypress and Spring before joining the San Jacinto River. The creek's watershed, which covers , is one of the largest in the county. The Brazos River straddles some of Houston's extreme western and southwestern suburbs, particularly Sugar Land and Rosenberg. Water bodies Houston contains few naturally formed lakes. Lake